alkanization of urine and barbiturates

 Q: Which of the following barbiturate requires alkalinization of urine?

A) short-acting

B) long-acting

Answer: B

Long-acting barbiturates like Phenobarbital requires alkalinization of urine. Short-acting barbiturates metabolized hepatically. When urine is alkalinized a lipid-soluble intact acid or base in the tubular lumen converts into the charged salt. The charged salt becomes lipid-insoluble and cannot move back across the epithelium, and excreted in the urine.

Few other drugs that respond well to alkalinization of urine include chlorpropamide,  salicylates, methotrexate, and sulfonamides. 

#toxicology

References:

1. Henry JA. Specific problems of drug intoxication. Br J Anaesth 1986; 58:223. 

2. Proudfoot AT, Krenzelok EP, Vale JA. Position Paper on urine alkalinization. J Toxicol Clin Toxicol 2004; 42:1.